In current producing Li/TiS.sub.2 systems, such as batteries, an important objective is to provide electrolytes having high conductivity (low specific resistivity) and whose shelf life and stability during operation of the system are sufficiently useful. It is, however, quite difficult to predict in advance the probability of the successful performance of non-aqueous electrolytes with any particular electrode couple.
It has been suggested that an electrolyte consisting of a solvent mixture of dioxolane and 1,2 dimethoxyethane could be used with complex lithium salts such as lithium hexafluoroarsenate, lithium hexafluorophosphate, and lithium tetrafluoroborate in Li/FeS.sub.2 battery systems. Such suggested electrolytes are to be found in the patent to: B. H. Garth, entitled "High Energy Density Battery with Dioxolane Based Electrolyte", U.S. Pat. No. 4,071,665, issued Jan. 31, 1978.
Similarly, it has been suggested that electrolytes of a similar character can be used in battery systems having an Li/V.sub.2 O.sub.5 couple. Such battery systems are described in the patent to A. Dey et al, entitled "Mixed Solvents for High and Low Temperature Organic Electrolyte Batteries", U.S. Pat. No. 3,947,289, issued Mar. 30, 1976. A. Dey et al recognize that certain electrolyte solvent(s) may undergo a polymerization, which increases the electrolyte impedance, and thus dramatically reduces their usefulness. A. Dey et al suggest the use of inhibitors to improve the shelf life of these electrolytes.
In the patent to M. R. Kegelman, entitled "Galvanic Cells Employing Uncompressed Particles of FeS as the Cathode", U.S. Pat. No. 4,084,045, issued Apr. 11, 1978, it is suggested that electrolytes using complex salts of lithium in a solvent mixture of 1,3 dioxolane and 1,2 dimethoxyethane can be employed in cells of the Li/FeS type.
It has been likewise suggested that simple salts of lithium such as lithium bromide, lithium iodide, etc., can be used in a dioxolane and dimethoxyethane solvent mixture for an Li/TiS.sub.3 electrochemical cell. Such a system is described in the patent to M. S. Whittingham et al, entitled "Alkali Metal/Niobium Triselenide Cell Having a Dioxolane-Based Electrolyte", U.S. Pat. No. 4,086,403, issued Apr. 25, 1978.
In an abstract (only an abstract available) to P. G. Gugla, entitled "Inefficiency Mechanisms in Plating and Stripping Lithium From a LiAsF.sub.6 Dioxolane Electrolyte", Journal of the Electrochemical Society, 126(11), Nov. (1979), 714 RNP, it is recognized that side reactions occur between the LiAsF.sub.6, dioxolane electrolyte and the lithium metal of the electrode, such that an insoluble lithium compound is formed resulting from dioxolane ring opening and water.
For use in the present current producing Li/TiS.sub.2 system of this invention, the proposed dioxolane containing electrolytes are not predictably suitable based upon the aforementioned teaching of Gugla.
When the proposed electrolytes containing the complex salts of lithium in a dioxolane solvent were first used in the present inventive Li/TiS.sub.2 system, certain instabilities were observed in particular situations in which starting materials and starting and storage conditions played an important part.
The use of these electrolytes in the inventive Li/TiS.sub.2 system has been found to require that these electrolytes generally have an aqueous pH equal to, or greater than, 6.00 in order to prevent polymerization of the dioxolane solvent.
As a general rule, it is necessary to choose the various solutes and solvents for these electrolytes so that they have a high elemental purity, since the probability of polymerization of the electrolyte increases with the increase of acidic impurities.